Apparatus for the control of highway crossing signals



Aug. 31, 1937. B. E. O'HAGAN ET AL 2,091,687

APPARATUS FOR THE CONTROL OF HIGHWAY CROSSING SIGNALS Filed Oct. 26, 1 9s5 ZSheets-Sheet 1 iNVENTO'RS Bernard E. Oliagan and Harold G. Witmer.

THEIR ATTORN EY Aug. 31, 1937. B. E. OHAGAN E AL 2,091,687

Q APPARATUS FOR THE CONTROL OF H IGHWAY CROSSING SIGNALS I Filed Oct. 26, 1955 2 Shets-Sheet '2 o N 3 w I N b N 3 N N n Q & x

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#5 Q. i Q s INVENTORS I BernanfEOHaganand HazvldGlZ/iimp. BY 1Q] flidlfwa Q 1 THEIR ATTORNEY Patented Aug. 31, I937 PATENT OFFICE APTARATUS FOR THE CONTROL OF HIGH- WAY CROSSING SIGNALS Bernard E. OHagan, Swissvale, and Harold G.

Witmel, Pittsburgh,

Pa., assignors to The Union Switch & Signal Company, Swissvale, Pa, a corporation of Pennsylvania Application October 26, 1935, Serial No. 46,914

13 Claims.

Our invention relates to apparatus for the control of highway crossing signals, and has for one object the provision of means for controlling a highway crossing signal in such a manner that after operation of the signal has been started by a train approaching the crossing and subsequently stopped as a result of the rear end of such trains passing a given point, operation of the signal may be restarted by a following train.

We will describe alternative forms of apparatus embodying our invention, and will then point out the novel features thereof in claims.

In the accompanying drawings, Fig. 1 is a diagrammatic view illustrating one form of apparatus embodying our invention applied to a stretch of single track railway; while Fig. 1d diagrammatically illustrates an alternative form of our invention.

Similar reference characters refer to similar parts in each of the views. 7

Referring to Fig. 1 of the drawings, the reference characters la and lb designate the rails of a stretch of railway track along which traflic normally moves in either direction. The track rails la and lb are intersected by a. highway H, provided with a signal S for warning highway trafiic of the approach of trains. Operation of the signal S is arranged to be started substantially when a train enters the track section DE. Thistrack section is provided with a track circuit including a track relay 'IR connected across rails in and It; at one end of the section and a source of track circuit current I0, connected across rails. la and lb in series with a resistor R at the other end of the section. Rail lb of section DE is also provided with three track instruments designated MI, M2, and M3, respectively.

The track instrument MI or M3 serves to initiate the operation of signal S when the section is entered, while M2 serves to insure continuance of operation of the signal until the train has passed over the crossing providing the train is moving at or above a predetermined minimum speed. Other functions under the control of track instrument M2 will be brought out later. The type of track instrument used is immaterial. However, for the purpose of this disclosure it may be assumed that each track instrument comprises a microphone of the type fully disclosed in Patent No. 1,834,077, issued December 1, 1931, to A. J. Sorensen. .A relay may be readily picked up in series with a track instrument of this type, but when a train passes the track which it is attached causes the resistance across its terminals to increase and thereby reduce the current flow through the relay below its holding value, and the relay accordingly releases.

The immediate operation of signal S is initiated by the release of one of two normally energized relays designated I and. 3, respectively. Relay I is normally energized over a pick-up circuit passing from terminal B of a suitable current source, through front contact 9 of track relay TR, wire l4, resistor RI, and the winding of relay I, toterminal C of the same current source. A stick circuit for relay I also passes from terminal B, through the front contact II of relay I, track instrument MI and then joins wire I 4. Stick and time element relays 5 and TE are arranged for control by relay I as will hereinafter be explained. The relay 5 may be of the ordinary quick-acting type, while {relay TE is'preferably of the type wherein a checking contact 13 opens immediately upon energization of the relay winding and wherein the remaining contacts of the relay are moved to their alternate position some time later. A relay of this type is disclosed in Patent No. 1,966,965, issued July 17, 1934, to B. Lazich and H. E. Ashworth. The relay 3 is identical to relay I, and is normally energized over a pick-up circuit including resistor R3, wire I6, and front contact 8 of relay TR. A stick circuit for relay 3 also passes from terminal B, through front contact 3I of relay 3, track instrument M3 and then joins wire I6. Relay 3 controls relays 6 and TE in the same manner that relay I controls relays 5 and TE. A relay designated 2, and which is similar to relays I and 3, is normally energized over a circuit including the back or checking contact I3 of relay TE and resistor R2. An alternative circuit for relay 2 includes track instrument M2 and resistor R2.

As will be apparent, with the track relay TR energized and its front contacts 8 and 9 closed, release of the relays I and 3 by their associated track instruments is prevented. Likewise, with the checking contact I3 of relay TE closed, release of relay 2 by track instrument M2 is prevented. It will be seen therefore that any operation of a track instrument, caused by workmen along the section or by a motor car which does not shunt the rails, will be without effect on its associated relay.

When, however, a train enters section DE from either direction track relay TR releases and at its front contacts 8 and 9 opens the pick-up circuits for relays 3 and I respectively. In the case of an eastbound train, it first passes over track instrument MI, and the actuation of this instrument effects the release of relay I. When relay I releases the front point of its contact I I opens the stick circuit for relay I, thereby removing relay I from further influence by its track instrument MI, while the back point of its contact II directly completes a pick-up circuit for relay 5. The relay I also closes circuits for relay TE and signal S, respectively. The circuit for relay passes from terminal B through the back con tact I2 of relay I, over wires I3 and I 3a to the left terminal of relay TE, and through the winding of TE to terminal C. The circuit for signal a S passes from terminal B through the back contact I2 of relay I, over wires I3 and I3a to the left terminal of relay TE, and then passes through back contact I2 of relay TE, and signal S, to terminal C. Operation of signal S accordingly starts at once. Relay 5 also picks up at once, and in addition to closing a stick circuit for itself including its front contact 5| and. the back contact 9 of track relay TR, it also at front contact 52 closes a circuit for relay 3 which includes wire I5 and resistor R3 and which circuit prevents the release of relay 3 by actuation of track instrument M3 when. the train later passes out of the section. The relay 5 also opens contact 53 to remove the condenser 20 from its multiple connection with relay 4 to prevent, as will be described later, the prolonging of the release time of relay 4 after an eastbound train has passed over track instrument M2. The time element relay TE also substantially immediately opens its checking contact I3, thereby placing the release of relay 2 under control of track instrument M2. The contacts 'II and I2 of relay TE are arranged to be actuated only after the circuit through the Winding of relay TE has been closed for a time interval greater than that required for a train, traveling at a predetermined minimum speed, to encounter track instrument M2.

If a train approaches the intersection at a very low speed, the relay TE will actuate its contacts II and I2 before the train encounters track instrument M2 and the circuit for signal S will be opened. by back contact I2 and operation of the signal S will be discontinued. When, subsequently, the train encounters track instrument M2, this track instrument efiects the release of relay 2, which closes the circuit for relay 4 at back contact 2I. Relay 4 therefore will pick up, and, being slow to release, will remain picked up while the train is passing over the track instrument M2 even though back contact 2| of relay 2 may be intermittently picked up while the train is passing over the track instrument. Relay 4 is provided with a. predetermined fixed slow release period and which release period is prolonged when the relay 5 is released by virtue of the condenser 20 being connected across the winding of relay 4 over back contact 53 of relay 5. When relay 4 picks up, it closes an alternative circuit for relay TE, which circuit passes from terminal B, through front contact 43 of relay 4, Wire I300, and the winding of relay TE, to terminal 0; and at front contact 44 closes a point in an alternative circuit for signal S which includes front contact II of relay TE. If, as previously explained, the train is traveling below a predetermined minimum speed, operation of the signal S will have been discontinued by the opening of contact I2 of relay IE, but .willbe again started by the closure of the alternative operating circuit for signal S including front contact II of relay TE.

If, as will ordinarily be the case, the train is traveling at or above the predetermined minimum speed the originally traced operating circuit for signal S will remain effective until after contact 44 is closed, then when relay TE sub sequently opens contact I2 operation of the signal will be continued over the second traced circuit including its front contact II. In either case, when relay 4 picks up, it closes a pick-up circuit for relay I, which circuit passes from terminal B, through front contact 42 of relay 4, wire I4a, resistor RI, and the winding of relay I, to terminal C. Relay I accordingly picks up and reestablishes its own stick circuit.

As soon as the rear end of the train passes beyond track instrument M2, relay 2 again picks up over the circuit including M2. After a slight delay which is equal to the aforementioned predetermined fixed released period of relay 4, relay 4 releases and at front contacts 43 and 44 opens the circuits for relay TE and signal S, respectively. The relay TE accordingly releases and the operation of signal S is discontinued.

If now before the train vacates section D-E a following train enters the section, track instrument MI will again effect the release of relay I. When relay I releases, its back contact I2 again closes the circuits for relay TE and signal S. The subsequent control of signal S, as the following train passes through the section will be the same as already described. When the section is Vacated, track relay TR again picks up, and, by opening the back point of its contact 9, opens the stick circuit for relay 5, which accordingly releases.

The circuits for controlling the signal S by Westbound trains are similar to those already described. There is a slight difierence however and this difference is because of the location of track instrument M2. Since track instrument M2 is to the right of the highway Hit is apparent that relay 4 will be maintained closed and operation of the signal will therefore be continued until after the rear end of an eastbound train has passed beyond the highway. However, in the case of westbound trains there is the possibility, unless the release time of relay 4 is increased, of relay 4 releasing before the rear end of a train passes beyond the highway. By including condenser 26 in multiple with the winding of relay 4 during westbound traflic movements the release time of relay 4 is somewhat prolonged, and so additional time is obtained for allowing the rear end of the train to clear the highway before operation of signal S is discontinued.

If desired the track instrument M2 may be placed. at a point midway between the sides of the highway H, in which case condenser 20 may be permanently connected across the terminals of relay 4.. With such an arrangement the slowrelease characteristic of relay 4 may be depended upon to insure operation of signal S until the rear end of the train has had time to pass beyond the highway irrespective of its direction of movement.

A further manner in which operation of signal S may be continued until after a train, moving in either direction, has positively cleared the highway is. to dispense with condenser 23 and its circuit connections and instead, as illustrated in Fig. 1a, provide a second track instrument M2a similar to M2, and a second relay 2a similar to 'and means controlled by said track relay for relay'Z. With the circuits of Fig. 1 modified in this manner, relay 4 is held picked up over a circuit including back contact 2| or 2la. until after the rear end of thetrain passes bothtrack instruments M2 and MM. In other respects the operation will be substantially the'same as already described.

It is to be observed thatif a train stopslbefor'e reaching the intersection the operation of the signal ceases when the slow'acting relay TE is picked up and the operation of the signal is not started until the head end of the train reaches the track instrument M2 in Fig. 1 or track insitrument M2 or MZa in Fig. 1a, the operation then continuing until the rear of the train clears the intersection. Such train would be moving at a very low speed when the head end reaches the intersection and would be required by train orders to approach the intersection at a low speed to avoid danger to the highway traffic. Again, the track instruments M2 and MM may be disposed so as to be actuated prior to arrival of a train at the intersection and restart to signal in case the train had stopped.

It will be seen from the foregoing that our invention covers a simple form of control apparatus for a signal at a highway intersecting a single track stretch of railway which has the advantage, over conventional apparatus of this character, that the control requires but one signal control track section.

Although we have herein shown and described only a few forms of apparatus embodying our invention, it is understood that various changes and modifications may be made therein within the scope of the appended claims without departing from the spirit and scope of our invention.

Having thus described our invention, what we claim is: i

1. In combination, a section of railway track intersected by ahighway and provided with a track circuit including a track relay, a highway crossing signal at the intersection, signal control means placed underthe'control of a train aprcaching the intersection by said track relay when the section is entered for initiating the operation of said signal before the train arrives at the intersection and for stopping its operation after the train has passed beyond the intersection, and means for causing the operation of said signal to be again initiated by said signal control means when a following train enters said section before the first train has vacated said section.

2. In combination, a section of railway track intersected by a highway and provided with a track circuit including a track relay, a highway crossing signal at the intersection, track instruments associated with a rail of the section having circuits and apparatus controlled thereby for initiating and stopping the operation of said signal during the progress of a train through the.

section, and means controlled by said track relay for at times preventing said track instruments from exercising any control over said circuits and apparatus.

3. In combination, a section of railway track intersected by a highway and provided with a track circuit including a track relay, a highway crossing signal at the intersection, a track instrument near each end of said section for starting the operation of said signal when a train enters said section from either end, a third track instrument at the intersection for continuing the operation of said signal until the rear end of the train passes beyond said third track instrument,

preventing the operation of said signal from being started while said track relay is energized.

4. In combination, a section of railway track intersected by a highway and provided with a track circuit including a track relay, a highway crossing signal at the intersection, a track instrument near each end of said section for starting the operation of said signal when a train enters said section from either end, a third track instrument at the'intersection for continuing the operationof said signal until the rear end of the train passes beyond said third track'instrument, means for causing the first encountered one of said track instruments to again start the operation of said signal when a following train or vehicle enters said section before it has been vacated by the preceding train or vehicle, and means controlled by said track relay for preventing the operation of said signal from being started while said track relay is energized.

5. In combination, a section of railway track intersected by a highway and provided with a track circuit including a track relay, a highway crossing signal at the intersection, a track instrument near each end of'said section for starting the operation of said signal after a train has entered said section from either end providing said track relay has been released, and other track instruments on opposite sides of the intersection having means controlled thereby for causing the operation of said signal to be continued until after the rear end of the train has passed beyond the intersection.

6. In combination, a section of railway track intersected by a highway and having a track circuit including a track relay, a signal at the intersection, track instruments near the respective ends of said section, circuits and apparatus jointly controlled by said track relay and one of said track instruments when a train enters the section from one end to startthe operation of said signal, other similar circuits and apparatus jointly controlled by said track relay and the other of said track instruments when a train enters the section from the other end to start the operation of said signal, a third and a fourth track instrument near the intersection, and circuits and apparatus associated with said third and fourth track instruments and influenced thereby to continue the operation of said signal until the rear end of the train passes beyond the intersection.

7. In combination, a stretch of railway track intersected by a highway, a highway crossing signal at the intersection, means actuated by a train after entering said stretch from either end for initiating the operation of said signal, equipment including signal control means in the vicinity of the intersection actuated by a train moving in either direction to continue the operation of said signal for a fixed interval of time after the rear end of a train has passed beyond said signal control means, and means for reducing the fixed interval of time of operation of said signal after the rear end of a train moving in a particular direction passes said signal control means.

8. In combination, a stretch of railway track intersected by a highway, a highway crossing signal at the intersection, means actuated by a train after entering said stretch from either end for causing said signal to be operated for a predetermined time period, other means subsequently actuated by a train moving in either .direction to eiTect operation of said signal for a predetermined time period after the rear end of the train has passed beyond said other means, and means for reducing such latter predetermined time period of operation of said signal when caused by a train moving in a particular direction.

9. In combination, a section of railway track intersected by a highway and provided with a track circuit including a track relay, a highway crossing signal at the intersection, a track instrument associated with said section and located to one side of the intersection, an auxiliary relay, an operating circuit for said signal including a back contact of said auxiliary relay, a pick-up circuit for the auxiliary relay including a front contact of the track relay, a stick circuit for the auxiliary relay including a contact of the track instrument, and another pick-up circuit for the auxiliary relay including a contact controlled by a train after it has advanced beyond the intersection and prior to Vacating the section whereby operation of the signal is effected when a following train enters the section before the first has vacated the section.

10. In combination, a section of railway track intersected by a highway at an intermediate point and provided with a track circuit including a track relay, a highway crossing signal at the intersection, a track instrument associated with the rail of the section at a selected location to one side of the intersection, an auxiliary relay, an operating circuit for said signal including a back contact of the auxiliary relay, a pick-up circuit for the auxiliary relay including a front contact of the track relay, a stick circuit for the auxiliary relay including a contact of the track instrument, another track instrument associated with the rail of the section at a location adjacent the intersection on the side opposite the first mentioned track instrument, another relay controlled over a contact of said other track instrument and. deenergized when said other track instrument is actuated, a slow acting relay, circuit means including a back contact of said other relay effective to energize said slow acting relay, and another circuit means including front contacts of the slow acting relay toenergize said auxiliary relay and to operate said signal.

11. In combination, a section of railway track intersected by a highway and provided with a track circuit including a track relay, a highway crossing signal at the intersection, a first track instrument remote from the intersection, control means governed by said track instrument for starting the operation of said signal when a train passes said instrument, a second track instrument adjacent the intersection, means controlled by said second track instrument for continuing the operation of said signal until the rear of the train passes beyond said second instrument, and means controlled by said track relay when energized for preventing either of said track instruments from operating the signal.

12. In combination, a stretch of railway track intersected by a highway, a highway crossing signal at the intersection, means actuated by a train upon entering said stretch for causing said signal to be operated for a predetermined time period, other means located adjacent the intersection and actuated by a train to eifect operation of the signal for a predetermined time period after the rear end of the train has passed beyond said other means.

13. In combination, a section of railway track intersected by a highway and provided with a track circuit including a track relay, a highway crossing signal at the intersection, two track instruments one near each end of said section, an auxiliary relay for each track instrument, means controlled by the track relay when deenergized for placing each auxiliary relay under the control of the associated instrument, means controlled by each auxiliary relay when released in response to a train actuating its track instrument to operate the signal, and means controlled by each auxiliary relay when released to remove the other auxiliary relay from control by its respective track instrument whereby operation of the signal as a train recedes from the intersection in either direction is avoided.

BERNARD E. OHAGAN. HAROLD G. WITMER. 

